U.S. patent number 10,355,332 [Application Number 15/235,258] was granted by the patent office on 2019-07-16 for electrolyte, lithium air battery including the electrolyte, and method of preparing the electrolyte.
This patent grant is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The grantee listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Kihyun Kim, Dongjoon Lee, Hyunpyo Lee, Minsik Park.
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United States Patent |
10,355,332 |
Lee , et al. |
July 16, 2019 |
Electrolyte, lithium air battery including the electrolyte, and
method of preparing the electrolyte
Abstract
An electrolyte including a polymer including a repeating unit
represented by Formula 1 and a lithium salt. Also a lithium air
battery and a method of preparing an electrolyte. ##STR00001##
Inventors: |
Lee; Hyunpyo (Seoul,
KR), Kim; Kihyun (Seoul, KR), Lee;
Dongjoon (Suwon-si, KR), Park; Minsik
(Hwaseong-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si, Gyeonggi-do |
N/A |
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO., LTD.
(Gyeonggi-do, KR)
|
Family
ID: |
58158060 |
Appl.
No.: |
15/235,258 |
Filed: |
August 12, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170054190 A1 |
Feb 23, 2017 |
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Foreign Application Priority Data
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Aug 19, 2015 [KR] |
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10-2015-0116962 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
10/0565 (20130101); H01M 10/0562 (20130101); H01M
12/08 (20130101); Y02E 60/10 (20130101); H01M
2300/0082 (20130101); Y02E 60/128 (20130101) |
Current International
Class: |
H01M
12/08 (20060101); H01M 10/0565 (20100101); H01M
10/0562 (20100101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1996031449 |
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Feb 1996 |
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JP |
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2012056925 |
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Mar 2012 |
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JP |
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2010083325 |
|
Jul 2010 |
|
WO |
|
Primary Examiner: Weiner; Laura
Attorney, Agent or Firm: Cantor Colburn LLP
Claims
What is claimed is:
1. An electrolyte comprising: a polymer comprising a repeating unit
represented by Formula 1; and a lithium salt, ##STR00025## wherein,
in Formula 1, ##STR00026## is a 5- to 31-membered group comprising
X, 1 to 30 carbon atoms, and optionally at least one heteroatom,
wherein the 5- to 31-membered group comprises an unsubstituted or
substituted C1-C30 cycloalkyl ring, an unsubstituted or substituted
C1- C30 heterocycloalkyl ring, an unsubstituted or substituted
C6-C30 aryl ring, or an unsubstituted or substituted C2-C30
heteroaryl ring, X is --S(.dbd.O).sub.2--,
--O--S(.dbd.O).sub.2--O--, --O--S(.dbd.O).sub.2--,
--S(.dbd.O).sub.2--O--C(.dbd.O)--O--S(.dbd.O).sub.2--, or
--S(.dbd.O).sub.2--O--S(.dbd.O)--O--S(.dbd.O).sub.2--, Z.sub.1 and
Z.sub.2 are each independently O or S, Y is a covalent bond, an
unsubstituted or substituted C1-C30 alkylene group, an
unsubstituted or substituted C6-C30 arylene group, an unsubstituted
or substituted C3-C30 heteroarylene group, an unsubstituted or
substituted C4-C30 cycloalkylene group, or an unsubstituted or
substituted C3-C30 heterocycloalkylene group, R.sub.1 to R.sub.8
are each independently a hydroxy group, a hydrogen atom, an
unsubstituted or substituted C1-C30 alkyl group, an unsubstituted
or substituted C1-C30 alkoxy group, an unsubstituted or substituted
C6-C30 aryl group, an unsubstituted or substituted C6-C30 aryloxy
group, an unsubstituted or substituted C3-C30 heteroaryl group, an
unsubstituted or substituted C3-C30 heteroaryloxy group, an
unsubstituted or substituted C4-C30 cycloalkyl group, or an
unsubstituted or substituted C3-C30 heterocycloalkyl group, a and b
represent mole fractions of corresponding structural units of the
polymer, wherein 0<a.ltoreq.1, 0.ltoreq.b.ltoreq.1, and a+b=1,
and n is an integer of 2 to 1000.
2. The electrolyte of claim 1, wherein ##STR00027## of Formula 1 is
represented by one selected from the group consisting of Formulae
2-1 to 2-8: ##STR00028## wherein, in Formulae 2-1 to 2-8, Q is C or
S, and R.sub.9 to R.sub.20 are each independently a covalent bond,
a hydrogen atom, a halogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group.
3. The electrolyte of claim 1, wherein ##STR00029## of Formula 1 is
represented by one selected from the groups consisting of Formulae
3-1 to 3-9: ##STR00030##
4. The electrolyte of claim 1, wherein the polymer comprising a
repeating unit represented by Formula 1 is represented by Formula
4: ##STR00031## wherein, in Formula 4, Y is a covalent bond, an
unsubstituted or substituted C1-C30 alkylene group, an
unsubstituted or substituted C6-C30 arylene group, an unsubstituted
or substituted C3-C30 heteroarylene group, an unsubstituted or
substituted C4-C30 cycloalkylene group, or an unsubstituted or
substituted C3-C30 heterocycloalkylene group, R.sub.3, R.sub.6, and
R.sub.8 are each independently a hydroxy group, a hydrogen atom, an
unsubstituted or substituted C1-C30 alkyl group, an unsubstituted
or substituted C1-C30 alkoxy group, an unsubstituted or substituted
C6-C30 aryl group, an unsubstituted or substituted C6-C30 aryloxy
group, an unsubstituted or substituted C3-C30 heteroaryl group, an
unsubstituted or substituted C3-C30 heteroaryloxy group, an
unsubstituted or substituted C4-C30 cycloalkyl group, or an
unsubstituted or substituted C3-C30 heterocycloalkyl group, a and b
represent mole fractions of corresponding structural units of the
polymer, wherein 0<a.ltoreq.1, 0.ltoreq.b.ltoreq.1, and a+b=1,
and n is an integer of 2 to 1000.
5. The electrolyte of claim 4, wherein ##STR00032## of Formula 4 is
represented by one selected from the group consisting of Formulae
3-1 to 3-9: ##STR00033##
6. The electrolyte of claim 4, wherein R.sub.3 and R.sub.4 are each
independently a hydrogen atom, a methyl group, an ethyl group, a
propyl group, a butyl group, or a pentyl group.
7. The electrolyte of claim 4, wherein R.sub.8 comprises at least
one selected from the group consisting of a hydroxy group, a
methoxy group, and an ethoxy group.
8. The electrolyte of claim 1, wherein the polymer comprises at
least one selected from the group consisting of a block copolymer
and a random copolymer.
9. The electrolyte of claim 1, wherein a weight average molecular
weight of the polymer is in a range of about 4,000 Daltons to about
100,000 Daltons.
10. The electrolyte of claim 1, wherein, in a thermogravimetric
analysis of the polymer, a temperature at which a weight of the
polymer reaches 90% of an initial weight is about 300.degree. C. to
about 340.degree. C.
11. The electrolyte of claim 1, wherein a molecular weight of the
polymer has a change of greater than 0 weight percent and less than
about 1 weight percent when analyzed by gel permeation
chromatography, when the polymer is contacted with Li.sub.2O.sub.2
at 20.degree. C. for 3 days in air.
12. The electrolyte of claim 1, wherein the electrolyte is solid at
a temperature of about 25.degree. C.
13. The electrolyte of claim 1, wherein the electrolyte comprises
less than 1 weight percent of a solvent, based on a total weight of
the electrolyte.
14. The electrolyte of claim 1, wherein the lithium salt comprises
at least one selected from the group consisting of of LiPF.sub.6,
LiBF.sub.4, LiSbF.sub.6, LiAsF.sub.6, LiN(SO.sub.2F).sub.2,
LiN(SO.sub.2C.sub.2F.sub.5).sub.2, LiN(SO.sub.2CF.sub.3).sub.2,
LiC.sub.4F.sub.9SO.sub.3, LiClO.sub.4, LiAlO.sub.2, LiAICl.sub.4,
LiN(C.sub.xF.sub.2x+1SO.sub.2)(C.sub.yF.sub.2y+1SO.sub.2) where,
3.ltoreq.x.ltoreq.20 and 3.ltoreq.y.ltoreq.20, LiF, LiBr, LiCl,
LiOH, Lil, LiB(C.sub.2O.sub.4).sub.2, and LiNO.sub.3.
15. A lithium air battery comprising a cathode; an anode; and an
electrolyte layer disposed between the cathode and the anode,
wherein the electrolyte layer comprises the electrolyte of claim
1.
16. The lithium air battery of claim 15, wherein the anode
comprises at least one selected from the group consisting of
lithium, a lithium alloy, and a metal alloyable with lithium.
17. The lithium air battery of claim 15, comprising further a gas
diffusion layer disposed on a surface of the cathode.
18. The lithium air battery of claim 15, wherein at least one
selected from the group consisting of the cathode, the electrolyte
layer, and the anode has a folded portion.
19. A method of preparing an electrolyte of claim 1, the method
comprising polymerizing a composition comprising a first monomer
represented by Formula 6 to prepare a polymer; and contacting the
polymer and a lithium salt together to prepare an electrolyte:
##STR00034## wherein, in Formula 6, ##STR00035## is represented by
one selected from the group consisting of Formulae 2-1 to 2-8:
##STR00036## wherein, in Formulae 2-1 to 2-8, Q is C or S, and
R.sub.9 to R.sub.20 are each independently a covalent bond, a
hydrogen atom, a halogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group, Y is a covalent bond, an
unsubstituted or substituted C1-C30 alkylene group, an
unsubstituted or substituted C6-C30 arylene group, an unsubstituted
or substituted C3-C30 heteroarylene group, an unsubstituted or
substituted C4-C30 cycloalkylene group, or an unsubstituted or
substituted C3-C30 heterocycloalkylene group, and R.sub.3 is a
hydroxy group, a hydrogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group.
20. The method of claim 19, wherein the composition further
comprises a second monomer represented by Formula 7: ##STR00037##
wherein, in Formula 7, R.sub.3 and R.sub.8 are each independently a
hydroxy group, a hydrogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of and priority to Korean
Patent Application No. 10-2015-0116962, filed on Aug. 19, 2015, in
the Korean Intellectual Property Office and all the benefits
accruing therefrom under 35 U.S.C. .sctn. 119, the content of which
is incorporated herein in its entirety by reference.
BACKGROUND
1. Field
The present disclosure relates to an electrolyte, a lithium air
battery including the electrolyte, and a method of preparing the
electrolyte.
2. Description of the Related Art
A lithium air battery includes an anode capable of incorporating
and deincorporating lithium ions, a cathode that oxidizes and
reduces oxygen in the air, and a separator disposed between the
cathode and the anode.
The lithium air battery uses lithium metal as an anode and air as a
cathode active material, and thus the cathode active material does
not need to be stored within the battery. Because the cathode
active material does not need to be stored in the battery, the
lithium air battery may have a high energy density. Lithium air
batteries have a high theoretical specific energy of 3,500
Watt-hours per kilogram (Wh/kg) or greater, which is about ten
times greater than that of a lithium ion battery.
SUMMARY
Provided is an electrolyte including a polymer.
Provided is a lithium air battery including the electrolyte.
Provided is a method of preparing the electrolyte.
Additional aspects will be set forth in part in the description
which follows and, in part, will be apparent from the description,
or may be learned by practice of the presented exemplary
embodiments.
According to an aspect of an exemplary embodiment, an electrolyte
includes a polymer including a repeating unit represented by
Formula 1; and a lithium salt:
##STR00002## wherein, in Formula 1,
##STR00003## is a 5- to 31-membered group including X, 1 to 30
carbon atoms, and optionally at least one heteroatom, wherein the
5- to 31-membered group includes an unsubstituted or substituted
C1-C30 cycloalkyl ring, an unsubstituted or substituted C1-C30
heterocycloalkyl ring, an unsubstituted or substituted C6-C30 aryl
ring, or an unsubstituted or substituted C2-C30 heteroaryl
ring,
X is --S(.dbd.O).sub.2--, --O--S(.dbd.O).sub.2--O--,
--O--S(.dbd.O).sub.2--,
--S(.dbd.O).sub.2--O--C(.dbd.O)--O--S(.dbd.O).sub.2--, or
--S(.dbd.O).sub.2--O--S(.dbd.O)--O--S(.dbd.O).sub.2--,
Z.sub.1 and Z.sub.2 are each independently O or S,
Y is a covalent bond, an unsubstituted or substituted C1-C30
alkylene group, an unsubstituted or substituted C6-C30 arylene
group, an unsubstituted or substituted C3-C30 heteroarylene group,
an unsubstituted or substituted C4-C30 cycloalkylene group, or an
unsubstituted or substituted C3-C30 heterocycloalkylene group,
R.sub.1 to R.sub.8 are each independently a hydroxy group, a
hydrogen atom, an unsubstituted or substituted C1-C30 alkyl group,
an unsubstituted or substituted C1-C30 alkoxy group, an
unsubstituted or substituted C6-C30 aryl group, an unsubstituted or
substituted C6-C30 aryloxy group, an unsubstituted or substituted
C3-C30 heteroaryl group, an unsubstituted or substituted C3-C30
heteroaryloxy group, an unsubstituted or substituted C4-C30
cycloalkyl group, or an unsubstituted or substituted C3-C30
heterocycloalkyl group,
0<a.ltoreq.1, 0.ltoreq.b.ltoreq.1, and a+b=1, and
n is an integer of 2 to 1000.
According to an aspect of another exemplary embodiment, a lithium
air battery includes a cathode; an anode; and an electrolyte layer
disposed between the cathode and the anode, wherein, at least one
of the cathode and the electrolyte layer includes the
electrolyte.
According to an aspect of another exemplary embodiment, a method of
preparing an electrolyte includes polymerizing a composition
including a first monomer represented by Formula 6 to prepare a
polymer; and contacting the polymer and a lithium salt together to
prepare an electrolyte:
##STR00004## wherein, in Formula 6,
##STR00005## is represented by one selected from the group
consisting of Formulae 2-1 to 2-8:
##STR00006## wherein, in Formulae 2-1 to 2-8, Q is C or S, and
R.sub.9 to R.sub.20 are each independently a covalent bond, a
hydrogen atom, a halogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group, Y is a covalent bond, an
unsubstituted or substituted C1-C30 alkylene group, an
unsubstituted or substituted C6-C30 arylene group, an unsubstituted
or substituted C3-C30 heteroarylene group, an unsubstituted or
substituted C4-C30 cycloalkylene group, or an unsubstituted or
substituted C3-C30 heterocycloalkylene group, and R.sub.3 is a
hydroxyl group, a hydrogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group.
BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects will become apparent and more readily
appreciated from the following description of the exemplary
embodiments, taken in conjunction with the accompanying drawings in
which:
FIG. 1A is a graph of intensity (arbitrary units, a.u.) versus
chemical shift (parts per million versus tetramethyl silane, ppm)
and is an NMR spectrum of a monomer used in Example 1;
FIG. 1B is a graph of intensity (arbitrary units, a.u.) versus
chemical shift (parts per million versus tetramethyl silane, ppm)
and is an NMR spectrum of a polymer prepared in Example 1;
FIG. 2A is a graph of intensity (arbitrary units, a.u.) versus
chemical shift (parts per million versus tetramethyl silane, ppm)
and is an NMR spectrum of a monomer used in Example 2;
FIG. 2B is a graph of intensity (arbitrary units, a.u.) versus
chemical shift (parts per million versus tetramethyl silane, ppm)
and is an NMR spectrum of a polymer prepared in Example 2;
FIG. 3A is a schematic view illustrating a structure of a lithium
air battery according to an exemplary embodiment;
FIG. 3B is a schematic view illustrating a structure of another
embodiment of a lithium air battery;
FIG. 4 is a graph of weight (%) versus temperature (.degree. C.)
and shows the results of a thermogravimetric analysis of polymers
prepared in Examples 1 and 2 and Comparative Example 1;
FIG. 5A is a graph of relative response (microvolts) versus time
(minutes) and is a gel permeation chromatography (GPC) molecular
weight distribution map before and after the polymer prepared in
Example 2 contacts Li.sub.2O.sub.2; and
FIG. 5B is a graph of relative response (microvolts) versus time
(minutes) and is a GPC molecular weight distribution map before and
after the polymer prepared in Comparative Example 1 contacts
Li.sub.2O.sub.2.
DETAILED DESCRIPTION
Reference will now be made in detail to exemplary embodiments,
examples of which are illustrated in the accompanying drawings,
wherein like reference numerals refer to like elements throughout.
In this regard, the present exemplary embodiments may have
different forms and should not be construed as being limited to the
descriptions set forth herein. Accordingly, the exemplary
embodiments are merely described below, by referring to the
figures, to explain aspects. As used herein, the term "and/or"
includes any and all combinations of one or more of the associated
listed items. "Or" means "and/or." Expressions such as "at least
one of," when preceding a list of elements, modify the entire list
of elements and do not modify the individual elements of the
list.
It will be understood that when an element is referred to as being
"on" another element, it can be directly on the other element or
intervening elements may be present therebetween. In contrast, when
an element is referred to as being "directly on" another element,
there are no intervening elements present.
It will be understood that, although the terms "first," "second,"
"third" etc. may be used herein to describe various elements,
components, regions, layers and/or sections, these elements,
components, regions, layers and/or sections should not be limited
by these terms. These terms are only used to distinguish one
element, component, region, layer or section from another element,
component, region, layer, or section. Thus, "a first element,"
"component," "region," "layer," or "section" discussed below could
be termed a second element, component, region, layer, or section
without departing from the teachings herein.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting. As
used herein, the singular forms "a," "an," and "the" are intended
to include the plural forms, including "at least one," unless the
content clearly indicates otherwise. "At least one" is not to be
construed as limiting "a" or "an." It will be further understood
that the terms "comprises" and/or "comprising," or "includes"
and/or "including" when used in this specification, specify the
presence of stated features, regions, integers, steps, operations,
elements, and/or components, but do not preclude the presence or
addition of one or more other features, regions, integers, steps,
operations, elements, components, and/or groups thereof.
Furthermore, relative terms, such as "lower" or "bottom" and
"upper" or "top," may be used herein to describe one element's
relationship to another element as illustrated in the Figures. It
will be understood that relative terms are intended to encompass
different orientations of the device in addition to the orientation
depicted in the Figures. For example, if the device in one of the
figures is turned over, elements described as being on the "lower"
side of other elements would then be oriented on "upper" sides of
the other elements. The exemplary term "lower," can therefore,
encompasses both an orientation of "lower" and "upper," depending
on the particular orientation of the figure. Similarly, if the
device in one of the figures is turned over, elements described as
"below" or "beneath" other elements would then be oriented "above"
the other elements. The exemplary terms "below" or "beneath" can,
therefore, encompass both an orientation of above and below.
"About" or "approximately" as used herein is inclusive of the
stated value and means within an acceptable range of deviation for
the particular value as determined by one of ordinary skill in the
art, considering the measurement in question and the error
associated with measurement of the particular quantity (i.e., the
limitations of the measurement system). For example, "about" can
mean within one or more standard deviations, or within .+-.30%,
20%, 10% or 5% of the stated value.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
disclosure belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
Exemplary embodiments are described herein with reference to cross
section illustrations that are schematic illustrations of idealized
embodiments. As such, variations from the shapes of the
illustrations as a result, for example, of manufacturing techniques
and/or tolerances, are to be expected. Thus, embodiments described
herein should not be construed as limited to the particular shapes
of regions as illustrated herein but are to include deviations in
shapes that result, for example, from manufacturing. For example, a
region illustrated or described as flat may, typically, have rough
and/or nonlinear features. Moreover, sharp angles that are
illustrated may be rounded. Thus, the regions illustrated in the
figures are schematic in nature and their shapes are not intended
to illustrate the precise shape of a region and are not intended to
limit the scope of the present claims.
A polymer electrolyte used in the lithium air battery may include a
polymer, such as polyethylene oxide (PEO) or poly(methyl
methacrylate) (PMMA). However, the polymer reacts with oxygen and
thus dissociates after exposure in the air for a long period of
time. Also, the polymer dissociates when it reacts with lithium
peroxide (Li.sub.2O.sub.2) that is generated during discharging of
the lithium air battery.
Therefore, a polymer with a high stability with respect to air and
lithium peroxide is needed.
Hereinafter, according to exemplary embodiments, an electrolyte, a
lithium air battery including the electrolyte, and a method of
preparing the electrolyte will be described in further detail.
The electrolyte according to an exemplary embodiment includes a
polymer including a repeating unit represented by Formula 1 and a
lithium salt:
##STR00007##
In Formula 1,
##STR00008## is a 5- to 31-membered group including X, 1 to 30
carbon atoms, and optionally, at least one heteroatom; wherein the
5- to 31-membered group includes an unsubstituted or substituted
C1-C30 cycloalkyl ring, an unsubstituted or substituted C1-C30
heterocycloalkyl ring, an unsubstituted or substituted C6-C30 aryl
ring, or an unsubstituted or substituted C2-C30 heteroaryl ring; X
is --S(.dbd.O).sub.2--, --O--S(.dbd.O).sub.2--O--,
--O--S(.dbd.O).sub.2--,
--S(.dbd.O).sub.2--O--C(.dbd.O)--O--S(.dbd.O).sub.2--, or
--S(.dbd.O).sub.2--O--S(.dbd.O)--O--S(.dbd.O).sub.2--; Z.sub.1 and
Z.sub.2 are each independently O or S; Y is a covalent bond, an
unsubstituted or substituted C1-C30 alkylene group, an
unsubstituted or substituted C6-C30 arylene group, an unsubstituted
or substituted C3-C30 heteroarylene group, an unsubstituted or
substituted C4-C30 cycloalkylene group, or an unsubstituted or
substituted C3-C30 heterocycloalkylene group; R.sub.1 to R.sub.8
are each independently a hydroxy group, a hydrogen atom, an
unsubstituted or substituted C1-C30 alkyl group, an unsubstituted
or substituted C1-C30 alkoxy group, an unsubstituted or substituted
C6-C30 aryl group, an unsubstituted or substituted C6-C30 aryloxy
group, an unsubstituted or substituted C3-C30 heteroaryl group, an
unsubstituted or substituted C3-C30 heteroaryloxy group, an
unsubstituted or substituted C4-C30 cycloalkyl group, or an
unsubstituted or substituted C3-C30 heterocycloalkyl group;
0<a.ltoreq.1, 0.ltoreq.b.ltoreq.1, and a+b=1; and n is an
integer of 2 to 1000.
The polymer represented by Formula 1 has an acrylamide backbone and
thus may have improved thermal resistance and chemical resistance
compared to other conventional polymers having a polyethyleneoxide
backbone or an acrylate backbone. Further, the polymer represented
by Formula 1 includes a stable polar group linked to the acrylamide
backbone and thus may provide improved ion conductivity without a
decrease in its stability. Therefore, an electrolyte including the
polymer represented by Formula 1 may simultaneously provide thermal
and chemical stability and ion conductivity.
In an exemplary embodiment, in Formula 1, n may be in a range of
about 10 to about 500. In an exemplary embodiment, in Formula 1, n
may be in a range of about 10 to about 250. In an exemplary
embodiment, in Formula 1, n may be in a range of 20 to 250.
In an exemplary embodiment, in the electrolyte,
##STR00009## of Formula 1 may be represented by one selected from
the group consisting of Formulae 2-1 to 2-8:
##STR00010##
In Formulae 2-1 to 2-8, Q is C or S, and R9 to R20 are each
independently a covalent bond, a hydrogen atom, a halogen atom, an
unsubstituted or substituted C1-C30 alkyl group, an unsubstituted
or substituted C1-C30 alkoxy group, an unsubstituted or substituted
C6-C30 aryl group, an unsubstituted or substituted C6-C30 aryloxy
group, an unsubstituted or substituted C3-C30 heteroaryl group, an
unsubstituted or substituted C3-C30 heteroaryloxy group, an
unsubstituted or substituted C4-C30 cycloalkyl group, or an
unsubstituted or substituted C3-C30 heterocycloalkyl group.
In an exemplary embodiment, in the electrolyte,
##STR00011## is a polar group, and in Formula 1 may be represented
by one selected from the group consisting of Formula 3-1 to 3-9,
but embodiments are not limited thereto, and any group suitable for
use as a stable polar group may be used:
##STR00012##
In an embodiment, in the electrolyte, a polymer including a
repeating unit represented by Formula 1 may be represented by
Formula 4:
##STR00013##
In Formula 4, Y is a covalent bond, an unsubstituted or substituted
C1-C30 alkylene group, an unsubstituted or substituted C6-C30
arylene group, an unsubstituted or substituted C3-C30 heteroarylene
group, an unsubstituted or substituted C4-C30 cycloalkylene group,
or an unsubstituted or substituted C3-C30 heterocycloalkylene
group; R.sub.3, R.sub.6, and R.sub.8 are each independently a
hydroxy group, a hydrogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group; 0<a.ltoreq.1,
0.ltoreq.b.ltoreq.1, and a+b=1; and n is an integer of 2 to
1000.
In an embodiment, in the electrolyte, a polymer including a
repeating unit represented by Formula 1 may be represented by
Formula 5:
##STR00014##
In Formula 5, R.sub.3, R.sub.6, and R.sub.8 are each independently
a hydroxy group, a hydrogen atom, an unsubstituted or substituted
C1-C30 alkyl group, an unsubstituted or substituted C1-C30 alkoxy
group, an unsubstituted or substituted C6-C30 aryl group, an
unsubstituted or substituted C6-C30 aryloxy group, an unsubstituted
or substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group; 0<a.ltoreq.1,
0.ltoreq.b.ltoreq.1, and a+b=1; and n is an integer of 2 to
1000.
In an embodiment,
##STR00015## which is a polar group in Formula 5 may be represented
by one selected from the groups consisting of Formula 3-1 to
3-9:
##STR00016##
In other embodiments, in a polymer including a repeating unit of
Formulae 1 to 5, R.sub.3 and R.sub.4 may be each independently a
hydrogen atom, a methyl group, an ethyl group, a propyl group, a
butyl group, or a pentyl group.
In an exemplary embodiment, in a polymer including a repeating unit
of Formulae 1 to 5, R.sub.8 may be a hydroxy group, a methoxy
group, or an ethoxy group.
The electrolyte may further include other polymers. The other
polymers may be any polymer that is suitable for use as an
electrolyte. In an exemplary embodiment, the electrolyte may
further include polyvinyl alcohol (PVA). However, in an exemplary
embodiment, the electrolyte may not include polyethylene oxide.
While not wanting to be bound by theory, in an electrolyte that
does not include polyethylene oxide polymer, the thermal and
chemical stability of the electrolyte may be improved.
In an exemplary embodiment, in the electrolyte, the polymer
including a repeating unit of Formulae 1 to 5 may be a block
copolymer or a random copolymer. In an exemplary embodiment, a
polymer including a repeating unit represented by Formulae 1 to 5
may be a block copolymer including a first polymer block formed of
a first repeating unit including a polar group, such as
##STR00017## and a second polymer block formed of a second
repeating unit that does not include the polar group. In an
exemplary embodiment, a polymer including a repeating unit
represented by Formulae 1 to 5 may be a random copolymer randomly
including a repeating unit including a polar group, such as
##STR00018## and a repeating unit that does not include the polar
group.
In an exemplary embodiment, in the electrolyte, a weight average
molecular weight of the polymer including a repeating unit
represented by Formulae 1 to 5 may be in a range of about 4,000
Daltons to about 100,000 Daltons, but embodiments are not limited
thereto, and the average molecular weight may be appropriately
changed. In an exemplary embodiment, in the electrolyte, a weight
average molecular weight of the polymer including a repeating unit
represented by Formulae 1 to 5 may be in a range of about 5,000
Daltons to about 80,000 Daltons. In an exemplary embodiment, in the
electrolyte, a weight average molecular weight of the polymer
including a repeating unit represented by Formulae 1 to 5 may be in
a range of about 6,000 Daltons to about 60,000 Daltons. In an
exemplary embodiment, in the electrolyte, a weight average
molecular weight of the polymer including a repeating unit
represented by Formulae 1 to 5 may be in a range of about 7,000
Daltons to about 50,000 Daltons. In an exemplary embodiment, in the
electrolyte, a weight average molecular weight of the polymer
including a repeating unit represented by Formulae 1 to 5 may be in
a range of about 8,000 Daltons to about 45,000 Daltons. When the
weight average molecular weight of the polymer including a
repeating unit represented by Formulae 1 to 5 is within these
ranges, thermal and chemical stability and ion conductivity of the
electrolyte may further improve.
In an exemplary embodiment, the glass transition temperature
(T.sub.g) of the polymer including a repeating unit represented by
Formulae 1 to 5 in the electrolyte may be in a range of about
40.degree. C. to about 90.degree. C. In an exemplary embodiment,
when a weight average molecular weight of the polymer including a
repeating unit represented by Formulae 1 to 5 is about 15,000, a
glass transition temperature (T.sub.g) of the polymer may be about
61.degree. C. In an exemplary embodiment, when a weight average
molecular weight of the polymer including a repeating unit
represented by Formulae 1 to 5 is about 30,000, a glass transition
temperature (T.sub.g) of the polymer may be about 85.degree. C.
In an exemplary embodiment, in a thermogravimetric analysis (TGA)
of the polymer in the electrolyte, a temperature at which a weight
of the polymer reaches about 90% of an initial weight may be about
300.degree. C. or higher. Since the temperature at which the
initial weight of the polymer decreases about 10% may be as high as
about 300.degree. C., the polymer may have improved thermal
stability. In an exemplary embodiment, in a TGA of the polymer in
the electrolyte, a temperature at which a weight of the polymer
reaches about 90% of an initial weight may be about 304.degree. C.
or higher. In an exemplary embodiment, in a TGA of the polymer in
the electrolyte, a temperature at which a weight of the polymer
reaches about 90% of an initial weight may be about 310.degree. C.
or higher. In an exemplary embodiment, in a TGA of the polymer in
the electrolyte, a temperature at which a weight of the polymer
reaches about 90% of an initial weight may be about 320.degree. C.
or higher. In an exemplary embodiment, in a TGA of the polymer in
the electrolyte, a temperature at which a weight of the polymer
reaches about 90% of an initial weight may be about 330.degree. C.
or higher. In an exemplary embodiment, in a TGA of the polymer in
the electrolyte, a temperature at which a weight of the polymer
reaches about 90% of an initial weight may be about 340.degree. C.
or higher.
In the electrolyte, the polymer may be inert with respect to the
air and lithium peroxide. For example, a molecular weight of the
polymer may not change after mixing and stirring the polymer with
Li.sub.2O.sub.2 for 3 days in the air. Since the polymer is inert
with respect to the air and lithium peroxide, the chemical
stability of the electrolyte including the polymer may improve, and
the lifespan characteristics of a lithium air battery including the
electrolyte may improve. In an exemplary embodiment, the polymer is
inert when the molecular weight of the polymer, as analyzed by Gel
permeation chromatography, has a molecular weight change of less
than about _1_wt % when contacted with Li.sub.2O.sub.2 at
20.degree. C. for 3 days in the air. In an exemplary embodiment, a
molecular weight of the polymer, as analyzed by Gel permeation
chromatography, has a molecular weight change of less than about
0.5 wt % when contacted with Li.sub.2O.sub.2 at 20.degree. C. for 4
days in the air. In an exemplary embodiment, the molecular weight
of the polymer, as analyzed by gel permeation chromatography, has a
molecular weight change of less than about 0.1 wt % when contacted
with Li.sub.2O.sub.2 at 20.degree. C. for 5 days in the air. In an
exemplary embodiment, the molecular weight of the polymer, as
measured by Gel permeation chromatography, has a molecular weight
change of less than about 0.01 wt % when contacted with
Li.sub.2O.sub.2 at 20.degree. C. for 7 days in the air.
The electrolyte may be in a solid state at a temperature of about
25.degree. C. or less. Since the electrolyte includes a polymer,
the electrolyte may be solid at room temperature. In an exemplary
embodiment, the electrolyte may be a solid at a temperature of
about 30.degree. C. or less. In an exemplary embodiment, the
electrolyte may be a solid at a temperature of about 35.degree. C.
or less. In an exemplary embodiment, the electrolyte may be a solid
at a temperature of about 40.degree. C. or less. In an exemplary
embodiment, the electrolyte may be a solid at a temperature of
about 45.degree. C. or less. In an exemplary embodiment, the
electrolyte may be a solid at a temperature of about 50.degree. C.
or less. That is, the electrolyte may be a solid polymer
electrolyte, which is a solid at room temperature.
Since the electrolyte is solid, a structure of a lithium air
battery may be simple. Also, problems, such as leakage, may not
occur, and thus stability of a lithium air battery may improve.
An In an exemplary embodiment, the ion conductivity of the
electrolyte may be about 1.times.10.sup.-9 Siemens per centimeter
(S/cm) or greater at 25.degree. C. When an ion conductivity of the
electrolyte is about 1.times.10.sup.-9 S/cm or greater at
25.degree. C., lithium ions may be transferred within the lithium
air battery. In an exemplary embodiment, an ion conductivity of the
electrolyte may be about 1.times.10.sup.-8 S/cm or greater at
25.degree. C. In an exemplary embodiment, an ion conductivity of
the electrolyte may be about 1.times.10.sup.-7 S/cm or greater at
25.degree. C. In an exemplary embodiment, an ion conductivity of
the electrolyte may be about 1.times.10.sup.-6 S/cm or greater at
25.degree. C. In an exemplary embodiment, an ion conductivity of
the electrolyte may be about 1.times.10.sup.-5 S/cm or greater at
25.degree. C. In an exemplary embodiment, an ion conductivity of
the electrolyte may be about 1.times.10.sup.-4 S/cm or greater at
25.degree. C. In an exemplary embodiment, an ion conductivity of
the electrolyte may be about 2.times.10.sup.-4 S/cm or greater at
25.degree. C. In an exemplary embodiment, an ion conductivity of
the electrolyte may be about 5.times.10.sup.-4 S/cm or greater at
25.degree. C.
The electrolyte may be a solvent-free electrolyte. In an exemplary
embodiment, the electrolyte may be a solid polymer electrolyte that
does not include a solvent and is formed of a polymer and a lithium
salt. When the electrolyte does not include a solvent, problems
related to a solvent, such as side reactions or leakage, may be
avoided. A content of a solvent in the solvent free electrolyte may
be less than 1 weight percent (wt %), less than 0.5 wt %, or less
than 0.1 wt %, based on a total weight of the electrolyte.
The solvent free electrolyte is different from a polymer gel
electrolyte, in which a solid polymer includes a small amount of a
solvent. For example, in the polymer gel electrolyte, an ion
conductive polymer includes a small amount of solvent, and thus the
polymer gel electrolyte may have increased ion conductivity.
Alternatively, the electrolyte may be a solvent-containing
electrolyte. The solvent-containing electrolyte may be an aqueous
electrolyte including an aqueous solvent or a non-aqueous
electrolyte including an organic solvent.
The non-aqueous (or organic) electrolyte may include an aprotic
solvent. The aprotic solvent may be, for example, a carbonate-based
solvent, an ester-based solvent, an ether-based solvent, a
ketone-based solvent, or an alcohol-based solvent. The
carbonate-based solvent may be, for example, dimethyl carbonate
(DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC),
dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl
carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate
(EC), propylene carbonate (PC), butylenes carbonate (BC), or
tetraethyleneglycoldimethylether (TEGDME). The ester-based solvent
may be, for example, methyl acetate, ethyl acetate, n-propyl
acetate, dimethylacetate, methylpropionate, ethylpropionate,
.gamma.-butyrolactone, decanolide, valerolactone, mevalonolactone,
or caprolactone. The ether-based solvent may be, for example,
dibutyl ether, tetraglyme, diglyme, dimethoxyethane,
2-methyltetrahydrofuran, or tetrahydrofuran. The ketone-based
solvent may be, for example, cyclohexanone. Also, the alcohol-based
solvent may be, for example, ethyl alcohol or isopropyl alcohol.
The aprotic solvent is not limited to the above examples and any
suitable aprotic solvent may be used.
Further, the aprotic solvent may be a nitrile such as R--CN
(wherein R is a straight, branched, or cyclic hydrocarbon group
containing 2 to 20 carbon atoms which may include a double-bond
aromatic ring or an ether bond), an amide such as
dimethylformamide, a dioxolane such as 1,3-dioxolane, or a
sulfolane.
The aprotic solvent may be used alone or as a mixture thereof, and
when the aprotic solvent is a mixture, a mixing ratio may be
appropriately changed according to the desired battery
performance.
The electrolyte includes a lithium salt. The lithium salt dissolves
in an organic solvent and may serve as a source of lithium ions in
a battery. For example, the lithium salt may catalyze movement of
lithium ions between a cathode and an anode.
An anion of the lithium salt included in the electrolyte may
include at least one of PF.sub.6.sup.-, BF.sub.4.sup.-,
SbF.sub.6.sup.-, AsF.sub.6.sup.-, C.sub.4F.sub.9SO.sub.3.sup.-,
ClO.sub.4.sup.-, AlO.sub.2.sup.-, AlCl.sub.4.sup.-,
C.sub.xF.sub.2x+1SO.sub.3.sup.- (where, x is a natural number),
(C.sub.xF.sub.2x+1SO.sub.2)(C.sub.yF.sub.2y+1SO.sub.2)N.sup.-
(where, x and y are a natural number), and a halide.
In an exemplary embodiment, the lithium salt included in the
electrolyte may include one or at least two of LiPF.sub.6,
LiBF.sub.4, LiSbF.sub.6, LiAsF.sub.6,
LiN(SO.sub.2C.sub.2F.sub.5).sub.2, Li(CF.sub.3SO.sub.2).sub.2N,
LiC.sub.4F.sub.9SO.sub.3, LiClO.sub.4, LiAlO.sub.2, LiAlCl.sub.4,
LiN(C.sub.xF.sub.2x+1SO.sub.2)(C.sub.yF.sub.2y+1SO.sub.2) (where, x
and y are 1 to 30), LiF, LiBr, LiCl, LiI, LiB(C.sub.2O.sub.4).sub.2
(lithium bis(oxalato) borate; LiBOB), lithium
bis(trifluoromethanesulfonyl)imide (LiTFSI), and LiNO.sub.3. but
embodiments are not limited thereto, and any suitable material
available as a lithium salt may be used.
In the solvent-free electrolyte, an amount of the lithium salt may
be in a range of about 0.001 wt % to about 30 wt % based on the
total weight of the solvent-free electrolyte, but the amount of the
lithium salt is not limited thereto, and the amount of the lithium
salt may be within any range that enables the electrolyte to
facilitate the transfer of lithium ions and/or electrons during
charging/discharging of the battery.
In the solvent-containing electrolyte, an amount of the lithium
salt may be in a range of about 100 millimolar (mM) to about 10
molar (M). In an exemplary embodiment, the amount of the lithium
salt may be in a range of about 500 mM to about 2 M. However, the
amount of the lithium salt is not limited thereto, and the amount
of the lithium salt may be within any range that enables the
electrolyte to facilitate the transfer of lithium ions and/or
electrons during charging/discharging of the battery.
According to another exemplary embodiment, a lithium air battery
includes a cathode; an anode; and an electrolyte layer disposed
between the cathode and the anode, wherein at least one of the
cathode and the electrolyte layer includes the electrolyte
described above. When the lithium air battery includes the
electrolyte, the thermal stability and chemical stability of the
battery may improve. Also, lifespan characteristics of the lithium
air battery may improve.
In the lithium air battery, the anode may include a lithium metal,
a lithium metal-based alloy, and/or a material capable of
intercalating or deintercalating lithium, but the anode is not
limited thereto, and any material that includes lithium or is
capable of intercalating or deintercalating lithium may be used as
an anode. The anode determines a capacity of the lithium air
battery, and thus the anode may be, for example, a lithium metal.
In an exemplary embodiment the lithium metal-based alloy may
include an alloy of lithium and, for example, aluminum, tin,
indium, calcium, titanium, or vanadium.
In the lithium air battery, the electrolyte layer may include a
separator. The separator may have any composition that is durable
within a usage range of the lithium air battery, and examples of
the separator may include a non-woven fabric formed of a
polypropylene material, a polymer non-woven fabric formed of a
polyphenylene sulfide material, and a porous film of an
olefin-based resin such as polyethylene or polypropylene, and the
separator may be used in a combination of two or more selected
therefrom.
The lithium air battery may further include a lithium ion
conductive solid electrolyte layer on at least one surface of the
cathode and/or the anode. For example, the lithium ion conductive
solid electrolyte layer serves as a protection layer that prevents
the lithium of the anode from directly reacting with impurities
such as moisture and/or oxygen that may be present the air.
In an exemplary embodiment, the lithium ion conductive solid
electrolyte layer may include a lithium ion conductive glass, a
lithium ion conductive crystal (ceramic or glass-ceramic), or a
mixture thereof, but the lithium ion conductive solid electrolyte
layer is not limited thereto, and any material that has both
lithium ion conductivity and that may protect a cathode and/or an
anode and that is available as a solid electrolyte layer may be
used. In an exemplary embodiment, the lithium ion conductive solid
electrolyte layer may be a lithium ion conductive oxide.
In an exemplary embodiment, the lithium ion conductive crystal may
include Li.sub.1+x+y(Al, Ga).sub.x(Ti,
Ge).sub.2-xSi.sub.yP.sub.3-yO.sub.12 (where, x and y satisfy
0.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1, or, for example,
0.ltoreq.x.ltoreq.0.4 and 0<y.ltoreq.0.6, or, for example,
0.1.ltoreq.x.ltoreq.0.3 and 0.1<y.ltoreq.0.4). In an exemplary
embodiment, the lithium ion conductive glass-ceramic may include at
least one of a lithium-aluminum-germanium-phosphate (LAGP), a
lithium-aluminum-titanium-phosphate (LATP), and a
lithium-aluminum-titanium-silicon-phosphate (LATSP).
The lithium ion conductive solid electrolyte layer may further
include an inorganic solid electrolyte component in addition to
glass-ceramic components. In an exemplary embodiment, the inorganic
solid electrolyte may include at least one of Cu.sub.3N, Li.sub.3N,
and LiPON.
The lithium air battery may further include a gas diffusion layer
disposed on one surface of the cathode. The air is provided to the
lithium air battery by diffusion of air through the gas diffusion
layer. The gas diffusion layer may be conductive. Due to the
conductivity, the gas diffusion layer may be used as a cathode
current collector. The gas diffusion layer may include a porous
carbonaceous material or a porous metal, but a material for the gas
diffusion layer is not limited thereto, and any material that is
suitable for use as a conductive gas diffusion layer may be used.
In an exemplary embodiment, the porous carbonaceous material may
include carbon fiber non-woven fabric. In particular embodiments,
the conductive carbonaceous gas diffusion layer has an energy
density that is lower than a metal, and thus when a lithium air
battery includes the conductive carbonaceous gas diffusion layer,
the energy density of the battery may increase.
In the lithium air battery, at least one of the cathode, the
electrolyte layer, and the anode may include a curved part. When at
least one of the cathode, the electrolyte layer, and the anode
includes a curved part, the lithium air battery may be curved once
or several times so that the overall shape of the lithium air
battery may be three-dimensional.
In an exemplary embodiment, the lithium air battery may be prepared
as follows.
First, a cathode is prepared. In an exemplary embodiment, the
cathode may be prepared as follows.
A carbonaceous material, a binder, and the electrolyte are mixed,
added to an appropriate solvent, and heated to prepare the cathode
slurry. Then, a surface of a current collector is coated with the
cathode slurry and then dried, or, optionally, the cathode slurry
is press-molded on the current collector to improve the electrode
density. The current collector may be a gas diffusion layer.
Alternatively, a surface of a separator or a solid electrolyte
layer may be coated with the cathode slurry and then dried, or,
optionally, the cathode slurry may be press-molded on the separator
or the solid electrolyte layer to improve the electrode
density.
The cathode slurry may optionally include a binder. The binder may
include a thermoplastic resin or a thermosetting resin. In an
exemplary embodiment, the binder includes at least one of a
polyethylene, a polypropylene, a polytetrafluoroethylene (PTFE), a
polyvinylidene fluoride (PVDF), a styrene-butadiene rubber, a
tetrafluoroethylene-perfluoroalkylvinylether copolymer, vinylidene
fluoride-hexafluoropropylene copolymer, a vinylidene
fluoride-chlorotrifluoroethylene copolymer, an
ethylene-tetrafluoroethylene copolymer, a
polychlorotrifluoroethylene, a vinylidene
fluoride-pentafluoropropylene copolymer, a
propylene-tetrafluoroethylene copolymer, an
ethylene-chlorotrifluoroethylene copolymer, a vinylidene
fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, a
vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene
copolymer, and an ethylene-acrylic acid copolymer. The above
binders may be used alone or as a mixture. The binder is not
limited to those listed above, and any suitable binder may be
used.
The current collector may be a porous structure having a net shape
or a mesh shape to increase the rate of oxygen diffusion, or the
current collector may be a porous metal plate of stainless steel,
nickel, or aluminum, but embodiments are not limited thereto, and
any suitable current collector may be used. The current collector
may be coated with an oxidation resistant metal or an alloy coating
layer to prevent or reduce the oxidation of the current
collector.
The cathode slurry may optionally include any suitable oxygen
oxidation/reduction catalyst and/or a suitable conductive material.
Also, the cathode slurry may optionally include a lithium
oxide.
The conductive material may be any material that has porosity and
conductivity, and an example of the conductive material may be a
porous carbonaceous material. In an exemplary embodiment, the
carbonaceous material includes at least one of carbon black,
graphite, graphene, activated carbons, and carbon fibers. The
conductive material may be a metallic conductive material such as a
metal fiber or a metal mesh. Also, the conductive material may
include a metallic powder that includes at least one of copper,
silver, nickel, and aluminum. The conductive material may be an
organic conductive material such as a polyphenylene derivative. The
conductive materials may be used alone or as a mixture thereof.
Next, an anode is prepared. In an exemplary embodiment, the anode
may be lithium metal as described above.
Then, an electrolyte layer is prepared. The electrolyte layer may
have a structure in which a separator is impregnated with the solid
polymer electrolyte. The electrolyte layer in which a separator is
impregnated with the solid polymer electrolyte may be prepared by
disposing a solid polymer electrolyte film on one or two surfaces
of the separator and then pressing the film and the separator
together. Alternatively, the electrolyte layer may be prepared by
injecting a liquid electrolyte, including but not limited to a
lithium salt, into the separator.
Next, the anode is disposed on one side of an external case, the
electrolyte layer is disposed on the anode, and the cathode
equipped with the lithium ion conductive solid electrolyte layer is
disposed on the electrolyte layer. Subsequently, the porous current
collector is disposed on the cathode, and a pressing member that
allows air to be delivered to the air electrode is disposed on the
porous current collector, thereby completing the manufacture of a
lithium air battery.
The external case may include an upper part that is in contact with
the anode and a lower part that is in contact with the electrode,
and an insulating resin may be disposed between the upper part and
the lower part to electrically insulate the electrode and the anode
from each other.
The lithium air battery may be used as a primary battery or as a
secondary battery. The shape of the lithium air battery may include
coin, button, sheet, stack, cylinder, flat, or cone shape. The
lithium air battery may also be a large-sized battery configured
for use in an electric vehicle.
In an exemplary embodiment, a lithium air battery 10 is
schematically shown in FIG. 3A. The lithium air battery 10 includes
a cathode 15 that is in contact with a first current collector 14
and uses oxygen as an active material; an anode 13 that is in
contact with a second current collector 12 and includes lithium;
and an electrolyte layer 16 that is disposed between the cathode 15
and the anode 13. A lithium ion conductive solid electrolyte layer
(not shown) may be further disposed between the cathode 15 and the
electrolyte layer 16. The first current collector 14 is porous and
thus may also serve as a gas diffusion layer 21 through which the
air may diffuse. A pressing member 19 that may transfer the air to
the cathode 15 is disposed on the first current collector 14. An
external case 11 is formed of an insulating resin material and is
disposed between the cathode 15 and the anode 13 to electrically
insulate the cathode 15 and the anode 13. The air is supplied
through an air inlet 17a and discharged through an air outlet 17b.
The lithium air battery 10 may be contained in a stainless steel
container.
In an another exemplary embodiment, referring to FIG. 3B, in the
lithium-air battery 10, the electrode-film assembly 18 may be
folded at an angle of about 180.degree. such that at least two
portions of the anode 13 overlap each other. Each of a first
surface 13c of the folded anode 13 and a second surface 13d
opposite to the first surface 13c may come into contact with the
composite electrolyte film 16, so that active metal ions may be
transferred to the anode 13. Therefore, the discharge capacity and
the energy density of the electrochemical cell 10 may be improved
compared to an electrochemical cell that has the same weight as the
electrochemical cell 10 and is able to transfer active metal ions
only to one surface to an anode.
Referring to FIG. 3B, in an electrochemical cell 10, an
electrode-film assembly 18 may include a cathode 15, an anode 13,
and a composite electrolyte film 16, and the electrode-film
assembly may comprise at least one folded portion, such as first
and second folded portions 18a and 18b as shown in FIG. 8. The
anode 13 included in the electrode-film assembly 18 may have at
least one folded portion, such as first and second folded anode
portions 13a and 13b as shown in FIG. 8. The cathode 15 may have
one or more folded portions, such as first and second folded
cathode portions 15a and 15b as shown in FIG. 8. The composite
electrolyte film 16 may have at least one folded portion, such as
first and second folded composite electrolyte film portions 16a and
16b as shown in FIG. 8.
Referring to FIG. 3B, in the electrochemical cell 10, the
electrode-film assembly 18 may be folded at an angle of about
180.degree. such that at least two portions of the anode 13 overlap
each other. Each of a first surface 13c of the folded anode 13 and
a second surface 13d opposite to the first surface 13c may come
into contact with the composite electrolyte film 16, so that active
metal ions may be transferred to the anode 13. Therefore, the
discharge capacity and the energy density of the electrochemical
cell 10 may be improved compared to an electrochemical cell that
has the same weight as the electrochemical cell 10 and is able to
transfer active metal ions only to one surface to an anode.
The term "air" as used herein is not limited to the air in the
ambient atmosphere and may include a combination of gases including
oxygen or pure oxygen gas. The definition of the term "air" may be
applied to other uses, such as, an air battery or an air
electrode.
According to another exemplary embodiment, a method of preparing an
electrolyte may include polymerizing a composition including a
first monomer represented by Formula 6 to prepare a polymer; and
mixing the polymer and a lithium salt together to prepare an
electrolyte:
##STR00019##
In Formula 6, Y is a covalent bond, an unsubstituted or substituted
C1-C30 alkylene group, an unsubstituted or substituted C6-C30
arylene group, an unsubstituted or substituted C3-C30 heteroarylene
group, an unsubstituted or substituted C4-C30 cycloalkylene group,
or an unsubstituted or substituted C3-C30 heterocycloalkylene
group; and R.sub.3 is a hydrogen atom, an unsubstituted or
substituted C1-C30 alkyl group, an unsubstituted or substituted
C1-C30 alkoxy group, an unsubstituted or substituted C6-C30 aryl
group, an unsubstituted or substituted C6-C30 aryloxy group, an
unsubstituted or substituted C3-C30 heteroaryl group, an
unsubstituted or substituted C3-C30 heteroaryloxy group, an
unsubstituted or substituted C4-C30 cycloalkyl group, or an
unsubstituted or substituted C3-C30 heterocycloalkyl group.
In the first monomer,
##STR00020## may have a structure represented by one selected from
the group consisting of Formulae 2-1 to 2-8 or one selected from
the group consisting of Formulae 3-1 to 3-9 as described in
connection with the electrolyte.
In the method of preparing an electrolyte, the first monomer
represented by Formula 6 may be prepared by reacting a monomer
including an acryloyl group with an amine such as
##STR00021##
A copolymer may be prepared when the composition further includes a
second monomer.
In the method of preparing an electrolyte, the composition may
further include a second monomer represented by Formula 7:
##STR00022##
In Formula 7, R.sub.3 and R.sub.8 are each independently a hydroxy
group, a hydrogen atom, an unsubstituted or substituted C1-C30
alkyl group, an unsubstituted or substituted C1-C30 alkoxy group,
an unsubstituted or substituted C6-C30 aryl group, an unsubstituted
or substituted C6-C30 aryloxy group, an unsubstituted or
substituted C3-C30 heteroaryl group, an unsubstituted or
substituted C3-C30 heteroaryloxy group, an unsubstituted or
substituted C4-C30 cycloalkyl group, or an unsubstituted or
substituted C3-C30 heterocycloalkyl group.
In the method of preparing an electrolyte, the polymer composition
may be prepared by solution polymerization, but embodiments are not
limited thereto, and any suitable method to prepare a polymer may
be used. Any suitable polymerization time and temperature may be
used.
In the mixing of the polymer and the lithium salt together, an
amount of the lithium salt may be in a range of about 0.001 wt % to
about 30 wt %, but the amount of the lithium salt is not limited
thereto and may be appropriately changed within a range that
provides desirable ion conductivity. The mixing of the polymer and
the lithium salt together may be performed by using any suitable
mixing method.
Hereinafter are definitions of substituents used in the chemical
formulas.
The term "alkyl" refers to fully saturated branched or unbranched
(or straight chain or linear) hydrocarbon groups.
Non-limiting examples of an alkyl group include methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl,
isopentyl, neopentyl, iso-amyl, n-hexyl, 3-methylhexyl,
2,2-dimethylpentyl, 2,3-dimethylpentyl, and n-heptyl.
One or more hydrogen atoms of the "alkyl" may be substituted with a
halogen atom, a halogen atom substituted C1-C20 alkyl group
(example: CF.sub.3, CHF.sub.2, CH.sub.2F, or CCl.sub.3), a C1-C20
alkoxy group, a C2-C20 alkoxyalkyl group, a hydroxy group, a nitro
group, a cyano group, an amino group, an alkylamino group, an
amidino group, a hydrazine group, a hydrazone group, a carboxyl
group or its salt, a sulfonyl group, a sulfamoyl group, a sulfonic
acid group or its salt, a phosphoric acid group or its salt, a
C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group,
a C1-C20 heteroalkyl group, a C6-C20 aryl group, a C6-C20 arylalkyl
group, a C6-C20 heteroaryl group, a C7-C20 heteroarylalkyl group, a
C6-C20 heteroaryloxy group, a C6-C20 heteroaryloxyalkyl group, a
C6-C20 heteroarylalkyl group, or a combination including at least
one of the foregoing, instead of hydrogen, provided that the
substituted atom's normal valence is not exceeded.
The term "cycloalkyl" refers to a monovalent group having one or
more saturated rings in which all ring members are carbon (e.g.,
cyclopentyl and cyclohexyl).
The term "heterocycloalkyl" refers to a cycloalkyl group including
at least one heteroatom selected from N, O, P, Si, and S. Here, the
"cycloalkyl" group is the same as defined above.
The term "halogen atom" includes fluorine, bromine, chlorine, or
iodine.
The term "alkoxy" refers to alkyl-O--, and the alkyl group is the
same as defined above. Non-limiting examples of an alkoxy group
include methoxy, ethoxy, propoxy, 2-propoxy, butoxy, tert-butoxy,
pentyloxy, hexyloxy, cyclopropoxy, and cyclohexyloxy. One or more
hydrogen atoms of the alkoxy group may be substituted with one or
more of the substituent groups described for the alkyl group
above.
The term "aryl" refers to an aromatic hydrocarbon system containing
one or more rings. Non-limiting examples of the aryl group include
phenyl, naphthyl, and tetrahydronaphthyl. One or more hydrogen
atoms in the aryl group may be substituted with the same
substituent groups as previously described for the alkyl group
above.
The term "heteroaryl" refers to a monocyclic or bicyclic organic
compound that includes at least one heteroatom selected from N, O,
P, Si, and S, and the remaining ring atoms are C. For example, the
heteroaryl group may include 1 to 5 heteroatoms and may include 5
to 10 ring members, wherein S and N may be oxidized to various
oxidation states. Non-limiting examples of a monocyclic heteroaryl
group include thienyl, furyl, pyrolyl, imidazolyl, pyrazolyl,
thiazolyl, isothiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl,
1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, 1,2,3-thiadiazolyl,
1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl,
isothiazol-3-yl, isothiazol-4-yl, isothiazol-5-yl, oxazol-2-yl,
oxazol-4-yl, oxazol-5-yl, isooxazol-3-yl, isooxazol-4-yl,
isooxazol-5-yl, 1,2,4-triazol-3-yl, 1,2,4-triazol-5-yl,
1,2,3-triazol-4-yl, 1,2,3-triazol-5-yl, tetrazolyl, pyrid-2-yl,
pyrid-3-yl, 2-pyrazin-2-yl, pyrazin-4-yl, pyrazin-5-yl,
2-pyrimidin-2-yl, 4-pyrimidin-2-yl, or 5-pyrimidin-2-yl.
The term "heteroaryl" also refers to a group in which a
heteroaromatic ring is fused to one or more aryl, cycloalkyl, or
heterocycloalkyl rings.
Non-limiting examples of a bicyclic heteroaryl include indolyl,
isoindolyl, indazolyl, indolizinyl, purinyl, quinolizinyl,
quinolinyl, and isoquinolinyl. One or more hydrogen atoms in the
heteroaryl group may be substituted with the same substituent
groups as previously described for the alkyl group above.
The term "heteroaryloxy" refers to heteroaryl-O--, and the
heteroaryl group is as described above.
The terms "alkylene", "arylene", "heteroarylene", "cycloalkylene",
and "heterocycloalkylene" refer to substituents, in which one
hydrogen atom of an alkyl group, an aryl group, a heteroaryl group,
a cycloalkyl group, and a heterocycloalkyl group is substituted
with a radical.
"Substituted" means a compound or radical substituted with at least
one (e.g., 1, 2, 3, 4, 5, 6 or more) substituents independently
selected from a halogen (e.g., F.sup.-, Cl.sup.-, Br.sup.-,
I.sup.-), a hydroxyl, an alkoxy, a nitro, a cyano, an amino, an
azido, an amidino, a hydrazino, a hydrazono, a carbonyl, a
carbamyl, a thiol, a C1 to C6 alkoxycarbonyl, an ester, a carboxyl,
or a salt thereof, sulfonic acid or a salt thereof, phosphoric acid
or a salt thereof, a C1 to C20 alkyl, a C2 to C16 alkynyl, a C6 to
C20 aryl, a C7 to C13 arylalkyl, a C1 to C4 oxyalkyl, a C1 to C20
heteroalkyl, a C3 to C20 heteroaryl (i.e., a group that comprises
at least one aromatic ring, wherein at least one ring member is
other than carbon), a C3 to C20 heteroarylalkyl, a C3 to C20
cycloalkyl, a C3 to C15 cycloalkenyl, a C6 to C15 cycloalkynyl, a
C5 to C15 heterocycloalkyl, or a combination including at least one
of the foregoing, instead of hydrogen, provided that the
substituted atom's normal valence is not exceeded.
Thereinafter, one or more embodiments An embodiment will be
disclosed in further detail with reference to the following
examples. These examples are for illustrative purposes and are not
intended to limit the scope of the disclosed embodiments.
EXAMPLES
Preparation of Polymer
Example 1
Poly(acrylamide-sulfolane)
In view of Reaction Scheme 1 below, 1.5 grams (g) of
3-aminomethylsulfolane was dissolved in 50 milliliters (mL) of
dichloromethane, and 1 g of triethylamine was added thereto to
prepare a reaction solution. The reaction solution was stirred at
0.degree. C. for 1 hour, and 0.7 g of acryloyl chloride was slowly
added thereto. Thereafter, the reaction solution was allowed to
react for 12 hours, a solvent was removed therefrom using a rotary
evaporator, and a monomer, as a reaction product, was purified by
column chromatography using a mixture of dichloromethane and
methanol at a volume ratio of 20:1.
1 g of the purified monomer was dissolved in dimethylformamide
(DMF), 0.004 g of azobisisobutyronitrile (AIBN) was added thereto
as a radical initiator, and the mixture was stirred for 2 days at
90.degree. C. to allow the polymerization reaction to occur. After
the polymerization was completed, the solvent was removed therefrom
using a rotary evaporator, and the poly(acrylamide-sulfolane)
polymer was obtained by precipitating with methanol.
A weight average molecular weight of the obtained polymer was
measured with respect to a polymethylmethacylate (PMMA) standard
sample by using gel permeation chromatography (GPC). A weight
average molecular weight of the obtained polymer was 12,000
Daltons.
As shown in FIGS. 1A and 1B, the difference in nuclear magnetic
resonance (NMR) peaks of the synthesized polymer and the monomer
confirmed that the polymer was obtained. In particular, a peak
corresponding to a vinyl group which appears at about 5.5 parts per
million (ppm) to about 6.5 ppm of the NMR spectrum of the monomer
shown in FIG. 1A was not observed in the NMR spectrum of the
polymer shown in FIG. 1B. Further, a plurality of sharp peaks that
appeared at about 1.5 ppm to about 3.5 ppm of the NMR spectrum of
the monomer shown in FIG. 1A appeared as broad peaks in the NMR
spectrum of the polymer shown in FIG. 1B.
##STR00023##
Example 2
Poly(methacrylamide-sulfolane)
In view of Reaction Scheme 2 below, 1.5 g of 3-aminomethylsulfolane
was dissolved in 50 mL of dichloromethane, and 1 g of triethylamine
was added thereto to prepare a reaction solution. The reaction
solution was stirred at 0.degree. C. for 1 hour, and 0.7 g of
methacryloyl chloride was slowly added thereto. Thereafter, the
reaction solution was allowed to react for 12 hours, a solvent was
removed therefrom using a rotary evaporator, and a monomer, as a
reaction product, was purified by column chromatography using a
mixture of dichloromethane and methanol at a volume ratio of
20:1.
1 g of the purified monomer was dissolved in dimethylformamide
(DMF), 0.004 g of azobisisobutyronitrile (AIBN) was added thereto
as a radical initiator, and the mixture was stirred for 2 days at
90.degree. C. to allow polymerization to occur. After the
polymerization was completed, the solvent was removed therefrom
using a rotary evaporator, and a poly(methacrylamide-sulfolane)
polymer, the polymerization product, was obtained by precipitating
with methanol.
A weight average molecular weight of the prepared polymer was
measured with respect to a polymethylmethacylate (PMMA) standard
sample by using gel permeation chromatography (GPC). A weight
average molecular weight of the prepared polymer was 19,000
Daltons.
As shown in FIGS. 2A and 2B, the difference in NMR peaks between
the prepared polymer and the monomer confirmed that the polymer was
obtained. In particular, a peak corresponding to a vinyl group that
appears at about 5.5 ppm to about 6.5 ppm of the NMR spectrum of
the monomer shown in FIG. 2A was not seen in the NMR spectrum of
the polymer, as shown in FIG. 2B. Also, a plurality of sharp peaks
that appear at about 1.5 ppm to about 3.5 ppm of the NMR spectrum
of the monomer shown in FIG. 2A, appeared as broad peaks in the NMR
spectrum of the polymer shown in FIG. 2B.
##STR00024##
Comparative Example 1
Poly(ethyleneoxide)
Polyethyleneoxide (PEO600k, available from Aldrich, 182028) was
used as is.
Comparative Example 2
Poly(methylmethacrylate)
Polymethylmethacrylate (Mw 15000 Daltons, available from Aldrich,
200336) was used as is.
Preparation of the Solid Electrolyte
Example 3
0.4 g of the polymer prepared in Example 1 was dissolved in 50 ml
of acetonitrile to obtain a polymer solution, 0.1 g of lithium
bis-trifluoromethanesulfonimide (LiTFSI) was then added thereto and
dissolved while stirring the solution, and the solution was poured
into a Teflon dish and dried at room temperature for 2 days. Then,
the solution was vacuum dried (at 60.degree. C. overnight) to
prepare an ion conductive polymer electrolyte in the form of a
film, from which residual solvent was removed. The electrolyte was
solid at 25.degree. C.
Example 4
An electrolyte was prepared in the same manner as in Example 3,
except that the polymer used was the polymer prepared in Example 2.
The electrolyte was solid at 25.degree. C.
Comparative Example 3
An electrolyte was prepared in the same manner as in Example 3,
except that the polymer used was the polymer prepared in
Comparative Example 2. The electrolyte was solid at 25.degree.
C.
Preparation of the Cathode
Example 5
The electrolyte prepared in Example 3 and a carbonaceous material
(carbon black, Printex.RTM., available from Orion Engineered
Chemicals, USA) were mixed in a weight ratio of 6:1 to prepare a
cathode slurry.
The cathode slurry was coated on a lithium-aluminum titanium
phosphate (LATP) solid electrolyte having a thickness of 250
micrometers (.mu.m) (available from Ohara Corp., Japan) at an
amount of 3.0 mg/cm.sup.2 (on an area of about 1 cm.times.1
cm).
Example 6
A cathode was prepared in the same manner as in Example 5, except
that the electrolyte prepared in Example 4 was used.
Preparation of the Lithium-Air Battery
Example 7
A separator (Celgard 3501) was disposed on a lithium metal thin
film anode.
0.05 mL of 1M LiTFSI in poly(ethyleneglycol)dimethylether (PEGDME)
(having a molecular weight of 500), as an electrolyte solution, was
injected into the separator.
The LATP solid electrolyte coated with the cathode prepared in
Example 5 was disposed on the separator so that the cathode was on
the top.
Then, a gas diffusion layer (GDL) (available from SGL, 25BC) was
attached on the cathode, a nickel mesh was disposed on the gas
diffusion layer, and a pressing member that allows air to be
transferred to the cathode was disposed thereon to press and fix
the cell, thereby completing the manufacture of a lithium air
battery.
An example of a structure of the lithium air battery is shown in
FIG. 3.
Example 8
A lithium air battery was prepared in the same manner as in Example
7, except that the cathode prepared in Example 6 was used.
Evaluation Example 1
Evaluation of Thermal Stability
The molecular weights of the polymers prepared in Examples 1 and 2
and the polymer prepared in Comparative Example 1 were measured in
a nitrogen atmosphere by using a thermal weight measurement
analysis device (TA Instrument Discovery series) using a
temperature ramp rate of 10.degree. C./min within a temperature
range of room temperature to 600.degree. C., and the results are
shown in Table 1 and FIG. 4. In Table 1, 95% and 90% denote
temperatures at which a weight of each of the polymers was reduced
to 95% and 90% of the initial weight, respectively.
TABLE-US-00001 TABLE 1 95% 90% Comparative 216.5.degree. C.
.quadrature. 247.6.degree. C. .quadrature. Example 1 Example 1
275.5.degree. C. .quadrature. 304.4.degree. C. .quadrature. Example
2 299.8.degree. C. .quadrature. 332.3.degree. C. .quadrature.
As shown in FIG. 4 and Table 1, the temperatures at which the
weights of the polymers prepared in Examples 1 and 2 decreased by
5% and 10% were higher than the temperatures at which the weight of
the polymer prepared in Comparative Example 1 decreased by 5% and
10%.
Therefore, the polymers of Examples 1 and 2 had improved thermal
stability relative to that of the polymer prepared in Comparative
Example 1. Further, the thermal stability of the polymer of Example
2 having a methacrylamide backbone was higher than that of the
polymer of Example 1 having an acrylamide backbone.
Evaluation Example 2
Evaluation of Chemical Stability
4 mg of the polymer prepared in Example 2 and 20 mg of
Li.sub.2O.sub.2 were added to 1 ml of dimethyl sulfoxide (DMSO),
stirred for 3 days, and a change in molecular weight distribution
of the polymer was observed by gel permeation chromatography (GPC).
A similar change in the molecular weight distribution of the
polymer prepared in Comparative Example 1 was observed for a sample
similarly treated. The results are shown in FIGS. 5A and 5B.
As shown in FIG. 5A, the maximum molecular weight of the polymer of
Example 2, after mixing with Li.sub.2O.sub.2 for 3 days, increased
from 12552 Daltons to 12683 Daltons, which was within the margin of
error for these measurements. This indicates that the polymer of
Example 2 was not decomposed under these conditions.
As shown in FIG. 5B, the maximum molecular weight of the polymer of
Comparative Example 1, after mixing with Li.sub.2O.sub.2 for 3
days, decreased from 180289 Daltons to 174564 Daltons. This
indicates that the polymer of Comparative Example 1 was at least
partially decomposed.
Since the polymer of Example 2 was not decomposed by the air and
Li.sub.2O.sub.2, it was determined that the polymer of Example 2
was inert with respect to the air and Li.sub.2O.sub.2 and
chemically stable.
Evaluation Example 3
Evaluation of Charging/Discharging Characteristics
At a temperature of 60.degree. C. in a 1 atmosphere (atm) oxygen
atmosphere, a charging/discharging cycle was performed on each of
the lithium air batteries prepared in Examples 7 and 8. The
charging/discharging cycle included discharging the batteries at a
constant current of 1 milliamperes per square centimeter
(mA/cm.sup.2) until a voltage of the batteries was 1.7 volts (V)
vs. Li and then charging the batteries with at same current until a
voltage of the batteries was 4.2 V vs. Li. Thus, it was confirmed
that the lithium air batteries were functional.
As described above, according to the one or more of the above
embodiments, a lithium air battery includes a polymer with improved
thermal and chemical stability, and thus thermal and chemical
stability of the lithium air battery may improve.
It should be understood that exemplary embodiments described herein
should be considered in a descriptive sense only and not for
purposes of limitation. Descriptions of features or aspects within
each exemplary embodiment should be considered as available for
other similar features or aspects in other exemplary
embodiments.
While an embodiment has been described with reference to the
figures, it will be understood by those of ordinary skill in the
art that various changes in form and details may be made therein
without departing from the spirit and scope as defined by the
following claims.
* * * * *